What is it?
The simultaneous bilateral knee prosthesis is a surgical intervention where the patient is implanted with two knee prostheses at the same time, that is to say, one in each knee.
Why is this procedure considered?
Approximately 20% of patients who undergo knee replacement surgery on one leg will have to undergo surgery on the other knee in the future. In this situation, it is possible to operate on both knees at the same time, simultaneously, in a single surgical intervention and a single anesthetic procedure. On the other hand, it is also possible to perform this operation in stages, that is to say, in a first operation one knee is operated on and, a few months later, the other one is operated on, as the doctor and the patient deem appropriate.
What are the advantages?
The simultaneous bilateral knee prosthesis, in comparison with the staged intervention, implies fewer days of admission (if we compare it with the accumulated days of admission of the two staged interventions). Since there is only one rehabilitation process (of both knees at the same time), we will have fewer days to return to previous activities. Patients with large deformities in both knees, with the simultaneous prosthesis, benefit from the correction of these deformities at the same time, avoiding dismetries (difference in length between the two legs because one deformity has been corrected and the other is still waiting to be operated). All this means greater final satisfaction for the patient. Finally, and from an economic point of view, the simultaneous intervention allows a reduction of costs in hospital centers and/or health systems because there is a single admission (with all the relevant expenses) and a single rehabilitation process.
What are the disadvantages?
The patient may suffer a number of complications, some fatal, associated with simultaneous intervention. Cardiopulmonary complications can occur, such as a heart attack, arrhythmia or pulmonary embolism; thromboembolic problems, where thrombi capable of obstructing arteries in any part of the body are generated; gastrointestinal problems such as paralysis of the intestines or an ulcer; states of confusion during hospitalization, etc.
Another disadvantage of simultaneous prostheses is the greater need for blood transfusion due to the greater loss of blood during the intervention of both knees at the same time.
Most published studies, when comparing patients operated on both knees simultaneously with patients operated on in stages, the results are unanimous in observing a higher risk of complication and need for transfusion in patients operated on simultaneously.
Can these drawbacks be reduced in simultaneous prostheses?
We currently have three tools that can reduce the disadvantages of simultaneous prostheses: patient selection, tranexamic acid and fast-track protocols.
Careful patient selection is essential to reduce complications in patients undergoing simultaneous surgery. Published studies show that in patients under 70 years of age, with controlled diabetes, without heart problems, not overweight (BMI less than 30) and with an ASA grade I or II classification, the risk of complications is minimal and, in addition, hospital stay is reduced.
Tranexamic acid is a drug used in traumatology and other medical specialties. Its function is to inhibit fibrinolysis, that is, to promote coagulation, allowing less bleeding during surgery. There are published studies which show that patients who have undergone simultaneous knee prosthesis surgery and who are administered tranexamic acid have a lower blood loss and a consequent need for transfusion.
The Fast-track protocol is a fast-track recovery program for patients who have undergone knee prosthesis surgery that reduces hospital stay, morbidity and patient convalescence in complete safety, without readmission. All this improves patient satisfaction. There are published studies where it is observed that patients operated on simultaneous knee prosthesis who follow a Fast-track protocol also have fewer complications, readmissions and need for transfusion.
Conclusions
Simultaneous bilateral knee replacement surgery can be safe in very selected patients following a Fast-track program and administered tranexamic acid. However, it should be kept in mind that there are some potential drawbacks with complications that, if they occur, can be fatal.